Conductivity-determining type impurity dopant compositions, such as borosilicates and phosphosilicates, are used extensively for doping semiconductor substrates to form pn junctions and contact areas. In some applications, the doped silicates are designed to perform other functions such as to serve as barrier regions, insulation regions, etc. In applications such as, for example, solar cells, it is desirable to dope the semiconductor substrate in a pattern having very fine lines or features.
In recent years, semiconductor production has utilized non-contact printers, such as ink-jet systems, to print doped silicates onto semiconductor substrates. Typically, the doped silicates are printed in desired areas and then thermally treated, such as by rapid thermal annealing, to cause the dopants to diffuse into the semiconductor substrates at the desired areas. However, dopants may diffuse beyond the desired areas into undesired areas during the process. This out-diffusion of dopants can significantly affect the electrical characteristics of the resulting semiconductor devices, particularly for those devices with doped patterns having very fine lines or features. Dopants having low out-diffusion are supposed to only dope the printed or coated area during high temperature annealing, without contaminating adjacent unprinted areas. If dopants are known to out-diffuse into adjacent unprinted areas, then an additional barrier pattern layer is needed to prevent the out-diffusion. Additional barrier pattern layers can significantly increase process complexity and cost.
Further, some dopant compositions for non-contact printing are not sufficiently room temperature stable and suffer from short shelf life. They may require refrigeration between their fabrication and their use. As a result, logistic, storage, and handling requirements for these dopant compositions can make their use cumbersome and uneconomical.
Accordingly, it is desirable to provide dopant ink compositions for forming doped regions in semiconductor substrates with reduced out-diffusion, and methods for fabricating such dopant ink compositions. In addition, it is desirable to provide dopant ink compositions for forming dopant regions in semiconductor substrates with increased stability at room temperature, and methods for fabricating such dopant ink compositions. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.